The curtain wall industry often utilizes aluminum frames/structures whose surfaces are coated finished to provide excellent appearance and structure protection (i.e., weather-proofing). This often involves an aluminum bar that has been extruded through a die where certain design specifications and characteristics are present, and applying decorative and protective finishes. Often a primer or etching material is used to enhance the bond strength between the substrate and finish. In more limited cases, but common in storefront applications, stainless steel is used which often requires special cleaning and priming steps.
In the curtain wall industry, it is required to have a high level of surface adhesion and/or bonding properties of the finished metal structures. ASTM C1401-7 is the standard guide for structural sealant glazing. Structural silicone adhesives have a good bonding affinity to glass because of similar chemistry, and also has a high expected bonding strength to metals, such as stainless steel or anodized aluminum. Aluminum structures with finishes, on the other hand, have a low surface energy if untreated.
A method of increasing surface energy/adhesion of architectural metal finishes in a curtain wall is desired and needed. In addition, some treatments such as stainless and anodized need surfaces properly cleaned of organic contaminants or residue salts from anodizing. Moreover, there is no currently accepted measurement method or indicator that may be used to forecast adhesion level after structural silicone curing other than destructive testing of the installed joint. Thus, there is a need and desire for a measurement method or indicator that may be used to forecast adhesion level after structural silicone curing.